1. Field of the Invention
The present invention relates to a handle apparatus for rotating an output shaft, which is used suitably for a mechanism for elevating and lowering, e.g., an objective lens and a stage of a microscope.
2. Related Background Art
A known prior art handle apparatus, disclosed in Japanese Patent Application Laid-Open Nos. 52-35656, 52-35657 and 52-53436, is capable of rotating an output shaft by switching the movement at such three stages as a rough movement, a medium movement and a fine movement. An outline of a conventional handle apparatus 200 will be explained with reference to FIG. 5. The following is an example of a construction thereof.
A slider 201 is fitted with a stage or an object lens (neither the stage nor the objective lens is shown) that are elevated and lowered integrally with the slider 201. A fixed support member 202 is inserted into the interior of the slider 201. Provided also is a pinion 204 engaging with a rack 203 formed in a side surface of the support member 202. The slider 201 is elevated and lowered by rotating the pinion 204, thus controlling a height of the unillustrated stage or objective lens. A central shaft 205 penetrating crosswise the slider 201 extends in the interior of the pinion 204. A couple of fine movement handles 206a, 206b, a couple of medium movement handles 207a, 207b and a couple of rough movement handles 208a, 208b are secured in sequence from the outside to ends of the central shaft 205 that protrude respectively in the right and left directions of the slider 201.
A frictional force adjustment ring 209 for controlling a driving torque of each handle is mounted at one side portion (which is a left portion in FIG. 5) of the slider 201. When rotating the frictional force adjustment ring 209 and each handle in such directions that they fasten each other, there must be needed a driving torque enough to rotate each handle. Reversely when rotating the frictional force adjustment ring 209 and each handle in such directions that they slacken each other, a small driving torque may suffice for rotating each handle. If the frictional force adjustment ring 209 is too slackened, however, it may happen that the slider 201 drops down by a self-weight thereof when separating the hand from the handle. It is therefore required that the frictional force adjustment ring 209 be properly fastened.
Further, a speed reduction device 210 for transmitting rotations of the respective handles to the pinion 204 is provided at the other side portion (which is a right side in FIG. 5) of the slider 201. As illustrated in the Figure, the speed reduction device 210 includes a multiplicity of gears. The rotations of each handle are properly decelerated through a gear train of the speed reduction device 210 and then transmitted to the pinion 204. With this operation, for example, the slider 201 is elevated and lowered on the order of several tens millimeters for one rotations of each of the rough movement handles 208a, 208b. The slider 201 is also elevated and lowered on the order of several millimeters for one rotation of each of the medium movement handles 207a, 207b. Then, the slider 201 is elevated and lowered on the order of 1 mm or less for one rotation of each of the fine movement handles 206a, 206b.